As conventional thermal transfer recording, there is a method in which a thermal transfer ink sheet comprising a substrate and provided thereon a thermomelting colorant layer or a colorant layer containing a sublimation dye is put face-to-face to a recording medium, and a heat source controlled by electrical signals given from a thermal head, an electrifying head or the like is brought into pressure contact with them from the side of the ink sheet to record an image by transfer. The thermal transfer recording has the features that it is noiseless, can be maintenance-free, is low in cost, can provide color images with ease and capable of performing digital recording, and is utilized in many fields of printers, recorders, facsimile systems and computer terminals.
Meanwhile, in recent years, in the field of medical treatment, printing and so forth, it is sought to provide recording processes feasible for what is called digital recording that can achieve a higher resolution and can process images at a high speed.
However, in conventional thermal transfer recording making use of a thermal head or an electrifying head as a heat source, it is difficult to make density higher, in view of the lifetime of head heating elements. To solve this problem, thermal transfer recording making use of a laser as a heat source is proposed in Japanese Patent Publications Open to Public Inspection [hereinafter referred to as Japanese Patent O.P.I. Publication(s)] No. 15437/1974, No. 17743/1974, No. 87399/1982 and No. 143659/1984.
In the thermal transfer recording making use of a laser as a heat source, resolution can be made higher by making a laser spot narrower. In the case when the recording is performed using a laser, it is common to carry out scanning recording. The scanning recording, however, has the disadvantage that its recording speed is lower than the recording speed achievable by the batch exposure making use of a masking material or the recording process making use of a line head. In order to increase the recording speed, it becomes necessary to increase scanning speed.
Methods for the scanning of laser beams include what is called plane scanning, in which primary scanning of laser beams is carried out using a polygonal mirror or galvanic mirror and an f-.theta. lens in combination and a secondary scanning is carried out while moving a recording medium, and cylindrical scanning, in which primary scanning is carried out while rotating a drum and secondary scanning is carried out by moving a laser beam. The cylindrical scanning is suited for heat mode recording because of its less energy loss in optical systems and capability of high-density recording. In this case, it is easy to increase scanning speed by increasing the rotational speed of the drum, but it is difficult to attain a close contact between a thermal transfer material and a recording material, which is necessary for the transfer. In the thermal transfer recording making use of a thermal head, it is possible to attain a close contact between a thermal transfer material and a recording material by virtue of the pressure acting between a platen and a thermal head heating element. In the cylindrical scanning, however, such a method can not be taken. Japanese Patent O.P.I. Publication No. 112665/1986 discloses that laser exposure is carried out while applying a pressure by means of a transparent pressing member. When, however, the drum is rotated at a high speed to carry out high-speed recording, it becomes difficult to apply a uniform pressure, tending to cause fogging due to contact uneveness or pressure transfer.
Meanwhile, a thermal transfer recording material comprising a support and having thereon an intermediate layer and an ink layer is proposed for the purpose of improving the contact between a recording material and an image receiving material, or for other reasons. For example, Japanese Patent O.P.I. Publication No. 225795/1985 discloses that a rubber type resin layer with a Young's modulus of 1.0.times.10.sup.8 Nm.sup.-2 at 50.degree. C. is provided in a thickness of 5 .mu.m or less between a support and a thermomelting colorant layer, whereby good printing can be carried out using a thermal head on sheets of paper including those with a high smoothness and those with a low smoothness.
Japanese Patent O.P.I. Publication No. 36698/1982 also discloses a thermal transfer sheet in which a resin layer comprised of polyvinyl butyral or epoxy, for improving adhesion between a support and an ink layer, is provided in a thickness of from 1 to 3 .mu.m as an intermediate layer to make cohesive failure readily take place in the ink layer so that the sheet can be used many times.
Japanese Patent O.P.I. Publication No. 138984/1982 further discloses a technique in which an adhesive layer comprised of a thermomelting polyamide and carbon black is provided in a thickness of 6 .mu.m as an intermediate layer so that only ink components can be permeated in and transferred to a recording paper without separation of an ink layer from the ink ribbon and printing can be repeatedly carried out. Japanese Patent O.P.I. Publication No. 116193/1983 discloses a technique concerned with a manufacturing process in which as an intermediate layer an adhesive layer similarly comprised of a thermomelting polyamide and carbon black is coated and dried followed by heating and then an ink layer is provided, which makes it possible to obtain an ink ribbon that can achieve a high printing density without causing separation of the ink layer from the support even when the intermediate layer has a smaller thickness. Japanese Patent O.P.I. Publication No. 109897/1985 discloses a technique in which a 1 to 2 .mu.m thick intermediate layer and a 2 to 4 .mu.m thick ink layer are provided on a 3 to 5 .mu.m thick PET film, where a rubber type latex or a synthetic rubber material is used in the intermediate layer, so that good printing can be performed even on a recording paper with a smoothness of from 100 to 300 seconds.
All of these techniques are clearly different from the technique for obtaining a good contact performance under a contact pressure (1.0 kg/cm.sup.2 at maximum) as weak as that in pressure reducing as intended in the present invention, and hence their inventive constitution is also different from the constitution of the present invention.
Japanese Patent O.P.I. Publications No. 144394/1986, No. 258793/1986, No. 279582/1986, No. 151393/1987, No. 5885/1989, No. 26497/1989 and so forth also disclose techniques concerning an image receiving medium having a cushioning layer between a support and an image receiving material. These, however, all relate to thermal transfer of a sublimation dye and also the heating is carried out by a thermal head. In addition, they are techniques applicable in instances in which an image once having been formed on an image receiving material is not required to be further transferred to a final recording medium. Hence, the techniques disclosed in these publications are different from the technique of the present invention.